Electrical system of distribution.



A. S. HUBBARD.

ELEOTRIGAL SYSTEM OF DISTRIBUTION. APPLICATION rum) JUNE e, 1906.

91 5,768. Patented Mar. 23, 1909.

IllflllllflllllllmlfllHHIIJIIHIIIII lterioration of the battery.

working circuit or circuits.

UNITED STATES PATENT. osrrrcii.

ALBERT S. HUBBARD, OF BELLEV-ILLE, NEW- JERSEY, ASSIGNOR TO GOULI) STORAGE BATTERY COMPANY, A CORPORATION OF NEW YORK. A

ELECTRICAL SYSTEM OF DISTRIBUTION.

Specification of Letters Patent;

Patented March 23, 1909.

Application filed runes, 1906. Serial No. 320,954.

' 'a citizen of the United States, and a resident of Belleville, Essex county, State of New Jersey, have invented certain new and useful Improvements in Electrical Systems of Distribution, of which the following is a specification. i

,My invention relates generally to electrical systems of distribution and especially to that class of system in which a storage battery is employed to steady the load on the generating system despite fluctuations of load in the My invention contemplates the employ- ,ment of a storage battery in connection both with a direct current system of distribution and an alternating current system of distribution, the regulation being such that the battery can. simultaneously compensate to steady the load on each of the generating.

plants, while, moreover, each generating plant may, independently of the battery, supply energy to the work circuits connected with the other enerating plantwhen the distribution of lhad between the two sys- This tends to reduce the losses in the batteryand the de- Between the alternating current and direct current sides of the systemI employ a motor enerator in which the'energy may be transferred either from alternating current energy to direct current energy, or vice versa. ,In the direct current circuit is the usualbattery and booster in series therewith actingas, a

source of auxiliary electro-motive force to vary the current flowing in the battery circuit. This booster I regulate in accordance with. the variations of current on the direct current side of the system and, preferably,

in accordance with the variations of the current strength of the direct current generating plant. The direct current and of the motor generator is regulated by means of various apparatus, hereinafter described, in accordance with changes in the alternating current circuit, .and, preferably, in accordance with changes of current strength of the alternating current generating plant. By this ar rangement any change of the direct current generator current causes the batterycircuit to be affected to charge or discharge to limit the variations of the direct current generator,

while any change of current strength of the alternating current generator plant will vary the electro-motive force produced at the direct current end of the motor generator and so cause a transference of energy from the direct current side of-the system to the alternating current side or vice versa in order to limit the change of current on the alternating current plant. If v o posite changes occur simultaneously on t e two sides of the system, then the tendency would be for energy to be transferred from one generating plant to the other without substantially altering the current flow in the battery circuit.' These results are obtained with the em loyment of only one booster and in a big y efficient manner.

Ordinarily the system operates in the general manner above set out but I also provide means, as another feature of my invention, to transfer the point at which the motor generator energy is taken or delivered to the current generator. This may be desirable for relieving thebattery at times either when the alternating current generator is shut down or when it is in operation. Thus, if the alternating current generator is in operation and the .direct current end of the motor generor relatively steady, cause the alternating current load to be taken entirely by the direct ator or rectifying device is connected between the direct current generator and the regulating coil the fluctuat1ons of load on the alternating current work circuit or such part of them as are-felt in the direct current side of the system will fall upon the main gen erator and not upon the battery. By the same arrangement I amenabled when the direct current generator is shut down to regulate the booster by changes in the alter-.

nating current work circuit since with the apparatus so connected the current to or from the direct current end of the rectifying device would pass through the regulating coil. r 7 Another feature of my invention resides in the regulatin set which I have prov ded, comprising smal regulating dynamos both for the booster and the direct current end of the motor generator controlled respectively 1 by the two sides of the system and driven by l the same motor.

Other features of my invention involve the various combinations and arrangements to more effectively and economically produce the desired regulation, as will more fully appear in the course of the following description.

The drawing accompanying this specification illustrates diagrammatically one embodiment of my invention.

A represents a direct current generator being merely" typical of any direct current source of power. Thus it is immaterial whether this is a single main generator, or whether there are a number of these generators. in parallel, or whether A represents only the direct current end or ends of one or more rotary converters at a substation. It is immaterial what. type of generator may be emplo ed and therefore i have not indicated t e field windings thereof.

B indicates an alternating current generator and is here represented as generating. three phase currents. Here, again, it is immaterial whether there is one or a number of alternating current generators at this. point, and it is equally immaterial what particular type of alternating current generator is employed.

1 is a direct current work circuit supplying current to any type or types of direct current translating devices. This circuit may be of considerable length and may or may not be at a considerable distance from either the direct current generator A or the alternating current generator'B or both.

2 represents an alternating current work circuit which also may be of considerable length and at any location relative to the generating plant or plants.

0, C represent respectively,the direct current end and the alternating current end of a motor generator. The direct current end isv connected to some part of the conductors leading from the generator A, while the alternating current end is connected to some part of the conductors leading from the generator B. The direct current end G of the motor'generator is preferably a differentially wound machine having windings c c for purposes hereinafter set out. The alternating current end C of the motor generator is preferably of the synchronous type in order that the motor generator may run at substantially synchronous speed. This mot-or generator is reversible in its transference of enorgy, that is, it may receive alternating current energy at C and deliver direct current energy at C or receive direct current energy at C and deliver alternating current energy at C. While I prefer a motor generatonand I the more specific features of my invention 1 include the provision of a motor generator at this point, yet the pertlcular function of i this motor generator isto transmit energy.

from'one side of the system to the other and in this sense it is merely a rectifying device.

So far as. my particular invention is concerned, therefore, any rectifying device, by which I mean, a device which receives alternating or direct currents and gives out direct or alternating currents may be employed.

D is a storage batte. j which is connected in series with the armature E of a booster, the branch containing the battery and booster being connected across the direct current side of the system, being therefore in parallel with the work circuit with refer ence to-the generator A and also in parallel with the motor generator with reference to the generator A. The booster armature E is driven by the armature F of a motor preferably connected to run at constant speed.

This motor, in the present instance, is shown as a motor having a shunt winding f, the motor being connected across the direct current circuit, but it is immaterial whether this motor is a direct current or an alternating current motor. In the present instance the fiowof' current through the motor generator or rectifying device and the flow of energy through the battery circuit are regulated by the resultant effects of changes of current on the direct current side of the system andon the alternating current side of the system.

The primary effect produced by the changes in the direct current side of the system are obtained by the following apparatus. G indicates a fixed resistance as, for example, the well known Weston type of shunt, located in the system where it will receive the current passing from the main generator A. To the terminals of this shunt is connected a circuit which includes the field coil h of a regulating dynamo. The current in this coil it will therefore vary in accordance with the changes of current of the main generator. 71. is a coil connected across the circuit and preferably arranged so that its current acts oppositely upon the field magnet of the regulating dynamo to that of the current in the coil it.

It will be understood, of course, that the resistance of the part of the circuit around which the coil '71. is connected may be manually adjusted in ways well known to the art to adjust the system for different average loads on the main generator. The armature H of this regulating dynamo is-connected in a separate branch across the direct current circuit, while in this branch in series with'the armature H. is the field coil of a regulating dynamo or exciter having the armature J.

The armature H is, therefore, in the present instance, the armature of a counter machine whose electro-motive force is opposed to that of the system, the resultant of these opposing electro-motive forces acting upon the field hereinafter described.

7' of the exciter. The currents generated by the armatureJ flow throu h the field e'of the booster and determine t e electrosmotive force produced by the booster. The counter electro-motive machine and; the exciterare preferably connected together mechanically and driven by the motor K, which is shown as having'a shunt winding 7c and is connected across the direct current system. I This motor also drives another regulating dynamo The specific means for exciting thefield of the booster in accordance withthe varie tions of current on the direct current gener-Y ator comprises the counter machine Hand exciter J, as above described, as well-as certain preferred. features of design and construction of these machines not herein described, do notform a part of the present invention, being the sub jectmatter of a separate application for Letters Patent which I am about to make, while someof the features ofthis apparatus have been set out in prior patents issued to me.

At L I have shown series transformers in the alternating current circuit, thesetbeing preferably located where their primaries will receive the current of the main alternating current generator B. These transformers are provided as part of the means for regulating in accordance with changes of current in the alternating current system, preferably the changes of current of the main generator thereof. The secondaries of these transformers have their terminals connected to the six brushes m of a rectifying apparatus M, which, in the present instance, is shown as a commutator driven by a synchronous motor N connected across the alternating current system. A direct current circuit leads from thebrushes m and this circuit is used for purposes of regulation. It will-be understood thatit is not material to my ,present invention what form of converting or rectifying apparatus is employed, or, in-

' deed, so far as my invention in its broadest phase is concerned, it is not essential that a rectifying device for the regulating circuit should be provided, although I deem it preferable and have therefore shown apparatus employing such apparatus in the embodiment of my invention illustrated. The direct current in'the circuit leading from the 'byjth'e handle S. These serve to adjust the system for different values of regulation and form no part of my present invention. Similar manually operated resistances T are also switch by means of which one branch of the armature -C- of the motor generator may be connected through the conductor U to the directc'urrent work circuit, which is the position of the switch shown in the drawing, or

- through the conductor U to a point between the generator A and the shunt G.

Inorder to" explain the operation of the system and the various apparatus Iwill assume that the generator A is giving a constantpotential at all timesregardless of the load u on the generator, it being, however, understood that the general operationof the system is not substantially difYcrent if generat'or A has a drooping or a rising characteristic. 1i

In order to make clear the action of the apparatus, we will assume the switch U to be in the position shown and first assume the system with a load on the direct current work circuit 1 exactly equal'to the average load desired on the generator A, and a load. on the alternating current work circuit 2 exactly equal to the load desired on the alternating current generator B. It will be assumed also that it is desired that each gener ator shall vary only within small limits'to each side of its desired average,the fluctuations in. the workcircuits and changes of condition of the battery being automatically compensated for by changes of current flow from the battery, or by transference of energy from the generator on one side of the 7 system to the work circuit on'the other side of the system, or by both. Under. these assumptions the system' will be" so adjusted that the current in the direct current work circuit will be entirely provided by the direct current generator A and the current in the alternating current work circuit 2 will be entirely provided by the alternating genbe in the following condition. The current from the secondaries of the transformers L will be just sufficient to'produce a field o-thatwill, through its action upon the armature O, produce a field strength,'due to the coils c and 0, just sufficient to cause the armature C to be run freely as a motor from the direct current circuit. The alternating current end C of the motor generator will also be receiving sufficient current from the alternating current circuit to run it freely. Thusthe work, of rotating the motor generator will be divided equally between the two circuits. t will be understood that this assumes an ideal exactitude which will not be met with ice ,generator for-this purpose.

in practice, nor is it of any importance that the system should be adjusted withsuchideal accuracy. Under these conditions, still assuming ideal accuracy, the current traversing the coil it will be just sufiicient so that the coils 7t and 71/ together will develop an elcctro-motive force in the armature H exactly equal 'to the voltage of the line. No current will therefore flow through the coil j and no electro-motive force will be reduced by the armature J so that the booster will be running idly. The battery D will be floating across the line neithercharging nor discharging. If now there is an increase ofv current on the direct current work circuit without other change of the system, a small portion of the change will fall upon the generator A and this small portion acting upon the coil it will cause the electro-motive force of the armature H to increaseor decrease. This change of the electro-motive force of H will cause a current to flow in the proper direction from the coil j thus producing a current from the armature J that will excite the booster field and produce a booster voltage in the proper direction to charge or discharge the batteries sufficiently to compensate for nearly all of the change that occurred in the working circuit. stantial change in the direct current working circuit will thus be compensated for, while, moreover, any change occurring at any moment in the battery condition, tending to vary the battery voltage and so to vary the current on the main generator, will also react through the coil h and the apparatus governed thereby to compel the proper battery current to flow.

Assume next that with the current on the direct current work circuit that corresponds to the desired average on the generator A there should be a substantial change of current on the alternating current work circuit. The moment that a small portion of this change is felt in the transformers L the current through the regulating rectifier to the coil 0 would be varied and this would cause a variation of current in the coil 0 of the direct current end of the'motorgenerator. The apparatus being suitably designed, this change will be sufficient tovary the'electromotive force of the armature O and at once, according to whether this change is an increase or a decrease, cause energy to be transferred by the motor-generator in one direction or the other to meet the change in the alternating current work circuit. Thus if the change in the alternating circuit is an increase, the end C of the motor generator will generate current to assist the generator B, while the direct current side of the system wills'upply the proper-energy to the motor This primary change caused by the alternating current Every sub' changes acting upon the field stren th of b will cause a secondary regulation of the tery,'because. the increased demand upon direct current side of the system, will cause the current in the coil h to change, as above described, and thereby vary the battery current in proper manner.

Assume now that both sides of the system change simultaneously and oppositely as, example, should there be an increase of load on the alternating current work circuit occurring simultaneously with a decrease of load on the direct current work circuit. If. we assume that these changes make the total load equal to the sum of the average loads of the two generators, less energy lost in the transformation, then the following distribution of currents would occur. .The increase on the alternating current work circuit acting I through the transformers L, the rectifier M, the dynamo O and the field a would cause the electro-motive force of C to decrease and transfer energy from the direct current sys} tem to the alternating current system. At the same time the decrease of current on the direct current work circuit would tend to.

cause current from the generator A to flow through the battery to charge it. The net result. obviously is to leave the battery floating on the system and to supply the needed extra energy at the alternating current cirycuit directly from the. direct current generator A through the motor generator;

- It will be seen that all sorts of conditions of distribution of load may be present, but the general method of operation remains the same. According to the condition of the two work circuits and the state of charge of the battery, either generator may be supplying any portion of its energy to the other circuit either with or without assistance from the battery, or either generator may be acting to charge the'battery and supply current to both work circuits. Putting it another way, either work circuit may receive its entire current from the generator of its side of the system, or it may also receive current from either the battery or from the generator on the other side of the system, or from both combined. Moreover, the flexibility of the system is such that either generator may be shut down entirely atcertain periods or when an emergency arises, and the other generator, assisted by the battery, may supply both work circuits, automatic compensation being effectually obtained.

It will be noted that the regulation by the fluctuations in the alternating current side of the system afiect the booster voltage just as those in the direct current side of the system affect that voltage. In the latter casethe fluctuations either inthe work circuit'or in the condition of battery react to vary the generatorcurrentand this causes a regulation the direct current side of the system.

tor circuit.

of the booster because of a change of current in the regulating coil it placed in the genera- In the former case the fluctuations in the alternating current side of the system act to regulate the transfer of energy either with conductor U or conductor U If connected to U" the armature C is connected in series with the'direct current work circuit so thatchanges of current in its armature Wlll act indirectly upon the booster inv the same manner as fluctuations of current in the direct current work circuit. If, however, the switch U connects the armature C with the conductor U then fluctuations of current in the armature C will, if the main generator A is in service, act to vary the current in the main generator without affecting the current in the regulating coil it so that these fluctuations, will not be compensated for by the battery D. This will be advantageous at times when it may be desirable to relieve the battery of some fluctuations occurring on the system. Again, this arrangement may be desirable when there is a com-. paratively light or steady load upon the alternating current workcircuit 2 and it is desired to shut down the main alternating current generator B. In thiscase the load on circuit 2 would simply be a'c'ontinuous load on the main generator A, the armature 0 being the armature of the motor driving 0 as the generator for the alternating current side of the system. Again, it the direct current generator A be shut down its connection to the armature 0 through the con- 1 ductor U willserve as a means of causing the current in the coil h to be regulated by the current from the armature G, since in this case the alternating current end of the rectifying device would be the motor and the direct current end would be the generator for the direct current side of the system, and the booster would act to regulate the battery in accordance with variations of current on what has now become the main generator for the direct current side of the system.

' It will be apparent that the various details of the apparatus ma be very widelymodified without departing om the scope of my invention, since various known metho s of regulating batteries and dynamos are now known and employed. I have simply chosen what I have considered preferable-apparatus for carrying out the various purposes which I have set out.

Having thus described my invention, what I claim as new and desire to protect by Letters Patent, is: a

, 1. The combination of an alternating current generator, a direct current generator, a battery in parallel with the direct current generator, .an' auxiliary source of electromotive force in series with the battery, a rectifying device between the alternating current and direct current circuits, and independent means for regulating the auxiliary source of electro-motive force and the direct current end of the rectifyin device, one of said means being controlled'by variations in the direct currentcircuit and the other by variations in the alternating current circuit.

2. The combination of an alternating current generator, a direct current generator, a battery in parallel with the direct current generator, an auxiliary source of. electromotive force in series with the battery, a rectifying device between the alternating current and direct current circuits, means for regulating the auxiliary source of electromotive force by variations of current in the direct current circuit, and means for regulat- 4 ing the electro-inotive force of the direct current end of the rectifying device by variations -of current in the alternating current circuit.

3. The combination of an alternating current generator, a direct current generator, a motor generator set between the same, a battery in parallel wi h the direct'current generator, a booster in series with the battery, means for regulating the current in the booster. field winding by variations of current in the direct current circuit and means for regulating the current in the field winding of the direct current end of the motor generator by variations of current in the alternating current circuit. I

4. The combination of an alternating cur- 're nt generator, a direct current generator, a

battery in parallel with the direct current generator, .an auxiliary source of electromotive force in series with the battery, a rectifying device between the alternatln current and direct current circuits, regu ating apparatus for the auxiliarv source of electromotive force, an independent regulating apparatus'for the direct current end of the rectifying device, one regulating apparatus being governed by fluctuations of, current strength of the direct current generator and one by the fluctuations of current strength of the alternating current generator.

V. 5. The combination of .an alternating curstrength of the direct current generator, and

vice by fluctuations of current strength of the alternating current generator.

6. The combination of an alternating current generator, a direct current generator, a motor generator set between the same, a battery in parallel with the direct current generator, a booster in series with the battery, means for regulating the current in the booster field winding by fluctuations of current strength of the direct current generator and means vtor regulating the current in the field Winding of the direct current end of the motor generator by fluctuations of current strength of the alternating current generator.

7. The combination of an alternating current generator, adirect current generator, a battery in parallel with the direct current generator, an auxiliary source of clectromotive force in series with the battery, it rectifying device between the alternating current and direct current circuits, independent means for regulating the auxiliary source of electro-motive force and the direct current end of the rectifying device, one of said means being controlled by variations in the-direct current circuit and the other by variations in the alternating current circuit,.

a direct current work circuit in connection with the direct current generator, the battery and the rectifying device, and an alternating current work circuit in connection with the alternating current generator and the rectifying device. 7 i

8. The combination of an alternating current generator, a direct current generator, a battery in parallel with the direct current generator, an auxiliary source of electromotive force in series with the battery, a

rectifying device between the alternating currentand direct current circuits, means for regulating the auxiliary source of electromotive force by variations of current in the direct current circuit, means for regulating the electro-motive force of the direct current end of the rectifying device by variations of current in the alternating current circuit, a direct current work circuit in connection with the direct currentv generator, the battery and the rectifying device, and an alternating current work circuit in connection with the alternating current generator and the rectifying device.

9. The combination of an alternating current generator, a direct current generator, a motor generator set between the same, a battery in parallel with the direct current generator, a booster in series with the battery, means for regulating the current in the booster lieldwinding by-variations of current .in the direct current circuit, and means for regulating the current in the field winding of the direct current end of the motor generator .by variations of current in the alternating current circuit.

10. The combination of an alternating current generatorand a circuit connected thereto, an alternating current work circuit, a direct current generator and a circuit connected thereto, a battery with its circuit and an auxiliary source of electro-motive force therein, a rectifying device having its alternating current end in parallel with the alternating current work circuit with relation to.

the alternating current generator circuit,

and its direct current end in parallel with the direct current work circuit and the battery circuit in relation to the direct current generator circuit, regulating means for the auxiliary source of electro-motive force and independent means for regulating the electromotive force of the direct current end of the rectifying device, said means being controlled one by changes in the alternating current generator circuit and one by changes in the direct current generator circuit.

11. The combination of a direct current generator, a storage battery, a booster in 'series withthe battery, a motor generator, an alternating current generator, alternating current and direct current work circuits, the battery circuit, direct current work circuit and direct current end of the mbtor generator being in parallel with relation to the direct current generator circuit, while the alternating current work circuit and the alternating current end of the motor generator are in parallel with relation to the alternating current generator, and independent means for regulating the booster field strength and the field strength of the direct current end of the motor generator, one of said means being dependent upon changes in the alternating current generator circuit and the other upon changes inthe direct current generator circuit. I

12. The combination of a direct-current generator, a storage battery,-a booster in series with the battery, a motor generator,

an alternating current generator, a ternating current and direct current Work circuits, the

tor being in parallel with relation to the direct current generator circuit, while the alternating current work circuit and the alternatingcurrent end of the motor generator are in parallel with relation to the alternating generator, means for regulating the booster field strength by changes of current strength in the direct current generator circuit, and means for regulating the field strength of the direct current end of the motor generator by changes of current strength in the alternating current generator circuit.

13. The combination of a direct current generator, a battery in parallel therewith, an alternating current generator, a rectifying device, means for varyii'lg the current of said rectifying device in accordance with the needs of the system, and means for causing the varying current of the rectifying device to substantially vary the direct current generator current or the battery current as desired. I

14;. The combination of a direct current generator, a battery in parallel therewith, an alternating current generator, a motor generator, automatic means for varying the direction and amount of the electrical energy transferred by said motor generator according to the needs of the system, and means for causing the variations of said energy to substantially vary the direct current generator load or the direct current battery load as desired.

15. Thecombination of a direct current generator, a battery in parallel therewith, a booster in the battery circuit, aregulating coil in the generator circuit for varying the booster electro-metive force, an alternating current generator, a rectifying device between the alternating current and direct current circuits, means for varying the electrical energy transferred from one circuit to the other by the rectifying device, and aswitch for connecting the direct current end of the rectifying device to either side of said regulating coil.

16. The combination of a direct current generator, a battery in parallel therewith, a booster in the battery'cireuit, an alternating current generator, a rectifying device between the alternating current and direct current circuits, and two regulating dynamos one regulating the booster field strength and itself controlled by variations of current strength in the direct current generator circuit, the other regulating the rectifying device and itself controlled by'variations of current strength in the alternating current generator circuit.

I 17. generator, a battery in parallel therewith, a booster in the battery circuit, an alternating current generator, a motor generator between the alternating current and direct current circuits, and two regulating dynamos, one regulating the booster field strength and itself controlled by variations of current strength in the direct current generator circuit, the other regulating the fieldstrength of the direct current end of the motor generator and itself controlled by variations of current strength in the alternating current generator circuit.

.18. The combination of a direct current generator, a battery in parallel thereuith, a .booster in the battery circuit, an alternating current generator, a rectifying device between the alternating current anddircct current circuits, t\=.o regulating dynamos, one'regulating the booster field strength and itself system.v I V The combination of a direct current- 'generator is out of circuit. The combination of a direct current controlled by variations of current strength in the direct current generator circuit, the

other regulating the rectifying device and itself controlled by variations of current strength in the alternating current generator circuit, and a motor mechanically connected to both regulating dynamos.

'19 The combination of a direct current enerato-r, a battery in parallel therewith, a

ooster in the battery circuit, an alternating current generator, a motor generator between the alternating current and direct current circuits, tvo regulating dynamos one legulating the booster field strength and itself controlled by variations of current strength in the direct currentgenerator circuit, the other regulating the field strength of the direct current end of the motor generator and itself controlled by variations of current strength in the alternating current generator circuit, and a motor mechanically connected to both regulating dynamos 20. In an electrical system of'distribution having a direct current generator, battery and booster, an alternating current generator, and a motor generator connecting the alternating current and direct current sides of the system, of a regulatingapparatus coniprising ar motor and trio exciting dynamos driven thereby and respectively exciting the booster and motor generator and responsive to fluctuations in the opposite sides of the '21. generator, a battery'm parallel therewith, an alternating current generator, a rectifying device betvceen the alternating current and direct'current circuits, a regu ating coil in the circuit of the direct current generator for varying the battery current, and means for' causing said coil to be responsive to changes of current in the direct current end of the rectifying device when the direct current 22. The combination of a direct current generatorya battery in parallel therewith, an alternating device between the alternatin current and direct current circuits, a regu ating coil for varying the battery current, and circuits and connections for causing said coil to be either in the circuit of thedirect current generator or in a circuit receiving the'algebraic sum of the currents of the direct current generator.

and direct current end of therectifying device out bf action, in the circuit of the direct current end of the rectifying devlce.

23. The combination of a direct current generator and work'circuit, an alternating current generator and work'circuit, a rectifying device betu een the alternating current and direct current sides of the system, a regulating battery direct'current circuit, a booster in the betor when the direct current generator is in a branch across the current generator, a rectifying tery branch and means for regulating the booster voltage responsively to fluctuations 111g current side of the system.

' 24. The combination of a direct current generator and york circuit, an alternating current generator and \z'ork circuit, a rectifying device bet. een the alternating current and direct current sides of the system, a regulating battery in a branch across the direct current circuit, a booster in the battery branch, a fieldwcinding for the booster,

and means for varying the current therein responsively to fluctuations on the direct current side of the systemand for modifying the direct current fluctuations responsively to fluctuations on the alternating current side of the system.

25. The combination of alternating current generatorand work circuit, a rectifying device connected thereto, .a battery and battery booster in series connected to the direct current end of the rectifying device, means for regulating the transfer of energy by said rectifying device, said means being responsive to changes on the alternating current side of the system, and means for regulating the booster voltage responsive to the changes of current in the direct current end of thercctifying device.

26. The combination of an alternating current generator, a direct current generator, a storage apparatus in parallel with the direct current generator, an auxiliary source of electro-Inotive force in series with the battery, a rectifying, device between the alternating current and direct current circuits, means controlled by variations in the direct current circuit in o erativerelation to Cbrrectioai n Letters Patent No. 915,768..

said auxiliary source of e ectro-motive force for regulating the same, and means conv [SEAL] It is hereby certified that in Letters Patent No. 915,768, upon the application of Albert S. Hubbard, of -Bel1eville, N ew Jersey, for an improvement in Electrical Systems of Distribution,

.tion requiring correction, as follows: In line 86, page Lafter the word trolledby variations in the alternating current circuit In operative relation wlth the said rectlfying device to regulate the ratio between the direct current and alternating a storage apparatus in parallel with the direct current generator, an auxiliary source of clectro-motive force in series with the battery, a rectifying device between the al ternating current and direct current circuits, a coil in the direct current circuit in operative relation to said auxiliary source of electro-motive force for regulating the same, and a coil in the alternating current circuit in operative relation with the said rectifying device to regulate the ratio between the direct current and alternating current electromotive forces thereof.

28. The combination of an alternating current generator, a direct current generator, a storage battery connected in parallel to the direct current generator, a booster in ithe battery circuit, a rectifying device between the alternating current and direct current circuits, .a coil in the direct current circuit subject to the fluctuations therein, regulating apparatus governed thereby and in operative relation with the field magnet of said booster, a coil in the alternating current circuit, and regulating apparatus governed by said coil and operatively related to said rectifying.

device to regulate the ratio between the alternating current and direct current electro-motive forces of the rectifying device.

In testimony whereof, I havesigned my name to this specification, in the presence of two subscribing witnesses.

ALBERT s. HUBBARD.

-Wit nesses EDWIN SEGER, ANNA DALY.

granted March 23, 1909,

an error appears in the printed specificadesirable the word also should beinserted and that the said Letters Patent should be read-with this correction therein that the same may conform to the record of the case in the Patent Signed and sealed this 20th day of April, A. 1)., 1909.

o. c. BILLINGS,

Acting Commissioner of Patents. 

